The most dangerous time to be involved with a paranoid controlling individual is when they fear they're losing control.
In abusive relationships the most dangerous time is when the abused attempts to leave, or end the relationship. that is why Battered women's shelters operate covertly to get victims out of the dangerous situation they are in
To a insignificant control freak something like his wife taking charge and possibly ending their marriage, against his desires would superseded his controlling way, that could be enough to push such an individual to act violently.
Though there was no evidence he was outwardly physically abusive there was evidence of emotional and psychological abuse.
In MANY cases, there's little outward sign of any trouble, until you look a little deeper into the relationship and if you know what your looking for you can often spot even potentially fatal red flags on the horizon. Since this is all hindsight, its 20/20
What you see is an individual who attempted to control all of those around him from his sisters love life to his own wife and children, in some cases, its not at all uncommon the following a divorce, male child starts to feel he is the man of the house.
Arrogance sometimes develops to compensate for inadequacy in adolescence m however in some individuals they lack the social skills to have a group of friends around them therefore its not until they meet someone willing to listen to their boasts that they feel they can say what they want.
In many cases, a woman looking for a guy who doesn't party much (because he doesn't have a large circle of friends) sticks to himself, likes, to hunt and fish, has served in the military , is in good shape and makes a decent wage is a catch, she's not asking for much is willing to deal with his controlling ways, accepts him both physically and emotionally (at first) therefore she becomes the perfect victim in their eyes.
And I mean "victim"
Individuals like this will often overcompensate for their inadequacies by a sometimes muted bravado, sometimes its not so muted and outright horrible , but something like trophy hunting or survivalism, and bragging about their abilities, bragging about how many sexual partners they had, would be examples, but that's not limited to just "manly" type activities, those who are religious devotees, they may claim to be more religious than others...they have few real friends or even emotional bonds , they want to be viewed as virile in some cases, macho but only where it counts to those close to him.
They tend to be reclusive in nature, which adds to the difficulty in apprehending them as they are completely fine out of the way, and can often find means on their own.
When they get into a relationship they often want to move quickly from dating to marriage to children, they invest everything in this little world they created, though it may be pure hell for everyone else in it, its their way or no way. they can be insanely jealous, at times, they tend to want to control all aspects of the marriage, money etc, they are often paranoid of outside influence, will do everything in their power to limit it, sometimes making them cut off friends and associates, making them account for their time and expenses, they control it its theirs, and so are the unlucky people in it .
They view the situation as a whole, everything in it is theirs, however, when that world is threatened as w whole they have zero issue disposing of it , including those in it. His wife , his children, their home ... At that point its an affront to his entire personna, one he will do away with because if he cant have it (the control, the false images, he created as a loving father and a good guy, the strong , hunter who can survive anything) none else will have it either.
Though there may not be these extremes in this case, those are common factors.
The victim taking control over a situation like that is him losing everything in his mind, and he wasn't going to have that . Especially if through infidelity they can mar his image and reputation.
The method of killing his wife and children is cold and efficient, the knife was most likely used because its silent compared to a gun, its also a means to prevent cry out. Its also very messy, he hoped the explosion and fire would destroy and scatter evidence enough that it would take long enough to find out what happened that he could be far away.
People don't pack all their clothes and take out money to go kill themselves.
Id think it was premeditated to the point that he had enough accelerant in the house to burn it down almost completely but I cant be certain what was used.
Did he have an accomplice? maybe, im not 100% certain he'd be living off the land for years now, I think he may've met someone who gave him a ride out of the area , possibly to the border where it wasnt as hard to cross back then .
The old adage is that people disappear south of the border, i think that's a likely scenario whether or not hell ever be apprehended or is even still alive is up for debate .